1. Field of the Invention
The invention relates to a directional coupler with directional transmission of high-frequency signals.
2. Related Technology
Coupled lines are conventionally used in directional couplers. In this context, reference is made, for example, to U.S. Pat. No. 5,689,217. However, with a conventional single-layer structure on a printed circuit board, only a low sharpness of directivity can be achieved. With the conventional structure, a sharpness of directivity of more than 30 dB can be achieved only with a structure of at least three layers or with a mechanically very complex structure or with an explicit optimization during manufacture of the sharpness of directivity of each individual directional coupler.